In the related art, there is a known light source apparatus in which a plurality of light sources that output light with different wavelength bands are combined (for example, see Patent Literature 1). In Patent Literature 1, a white-light source having a light-emission spectrum in the entire visible light region and an excitation-light source that outputs light in a comparatively narrow wavelength band are used. The spatial intensity distributions of the white light and the excitation light separately output from the two light sources differ from each other. Therefore, to irradiate the same position on a specimen with the white light and the excitation light to perform accurate analysis, it is necessary to make the spatial intensity distributions of these two types of light the same at the irradiation position. In Patent Literature 1, by shifting the focal position of a lens that focuses the white light and the excitation light at an entrance end of a light guide in the optical-axis direction from the entrance end, the difference between the intensity distributions of the white light and the excitation light at the entrance end can be minimized.
In recent years, semiconductor light sources such as LEDs have come to be used instead of lamp-type light sources such as the white-light source and excitation-light source described above. Semiconductor light sources have features such as long lifetime, high efficiency, high response, and so forth. The wavelength band of the light output from semiconductor light sources is narrow. Therefore, if light with a wide wavelength band is needed, a plurality of semiconductor light sources are used in combination, and beams of light with a plurality of wavelengths are combined.
The angular characteristics of the light output from a semiconductor light source differ depending on the material and structure of the chip, or the structure of the package etc. The angular characteristics of the light are maintained even while the light is guided through a light guide. Therefore, just by adjusting the intensity distributions of the light at the entrance end of the light guide, as in Patent Literature 1, due to differences in the angular characteristics of each type of light after being emitted from the light guide, a difference between the light intensity distributions occurs, and as a result, color unevenness occurs at the irradiation position on the specimen.